AI agents call list_labels to retrieve information from Mail without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns label/flag metadata without creating, modifying, deleting, or executing anything. It is a pure read operation that retrieves information about email organizational metadata. The blast radius of misuse is minimal — an agent could learn about label structures but cannot alter them or access email content directly through this tool.
From the tool's definition Tool description states it 'List[s] all user-defined keyword labels available on a folder' — a retrieval operation with no modification or side effects. The reference to PERMANENTFLAGS is a standard IMAP query mechanism for listing metadata.
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
List all user-defined keyword labels available on a folder (PERMANENTFLAGS). It is categorised as a Read tool in the Mail MCP Server, which means it retrieves data without modifying state.
Register the Mail MCP server in PolicyLayer and add a rule for list_labels: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Mail. Nothing to install.
list_labels is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_labels rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for list_labels. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
list_labels is provided by the Mail MCP server (kpihx/mail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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